Lower alkenals

ABSTRACT

Novel lower 2-alkylidene-2-alkenals having the formula:

BACKGROUND OF THE INVENTION

The present invention provides novel alkylidene alkenals useful foraltering the organoleptic properties of consumable materials such asfoodstuffs, tobacco products, and perfumes.

U.S. Pat. No. 3,463,818 shows unsaturated aldehydes having variousfloral odors and processes for preparing such compounds. Japanesepublished application 72/43526 shows the synthesis of terpenederivatives having orange-like odors, and hexadienal derivatives areshown. Wiemann et al, Bul. Soc. Chem. de France Memoires Presentes Soc.Chim., 1966, 1760, describe nuclear magnetic residence studies on someconjugated dienals, and a number of these compounds, including2-ethylidene-3-pentenal are shown. 2-Propenyl-2-pentenal is mentioned inChem. Abstracts 35, 6238.

West German published application 1,951,883 is said in Chem. Abstracts75, 5246 to show preparation of dienals useful as perfumes. Tiffeneau etal, Comptes Rend. 204, 590 show the preparation of2-alkylidene-3-butenal.

U.S. Pat. Nos. 3,272,873; 3,453,317; and 3,493,619 show processes forpreparing unsaturated aldehydes or for treating such aldehydes. U.S.Pat. No. 3,520,936 shows production of an unsaturated aldehyde, and U.S.Patent 3,542,878 shows an aldol condensation using a tin catalyst.

Odiger et al Annalen 682 58; Corey et al, J. Am. Chem. Soc. 90, 6816;and Wittig et al, Chem. Ber. 94 676 show alkylidenation reactionsutilizing phosphorus compounds. Goldberg et al shows selective reductionof unsaturated Schiff base systems in J. Am. Chem. Soc. 77, 1955.

THE INVENTION

The present invention provides novel 2-alkylidene-3-alkenals useful foraltering the organoleptic properties of consumable materials. Briefly,the novel compounds are 2-alkylidene-3-alkenals having the formula:##SPC2##

Wherein one of R₁ and R₂ is hydrogen and the other is methyl, and one ofR₃ and R₄ is hydrogen and the other is an alkyl group containing two orfour carbon atoms.

Thus, the alkyl groups contemplated according to the present inventionare lower alkyl groups. Preferably the alkyl groups represented by R₃and R₄ are ethyl or isobutyl.

It will be understood from the present disclosure that several"cis-trans" isomers are possible as a result of the presence ofsubstituents on the carbon atoms surrounding the carbon-carbon doublebond of the alkenal chain as well as the alkylidene moiety and suchisomers are contemplated herein. As an instance, a particularlypreferred alkenal is trans-2-ethylidene-cis-3-hexenal, the compoundaccording to the foregoing formula when R₁ is methyl and R₃ is ethyl.The structure of this compound can be written: ##SPC3##

with the methyl group trans to the carbonyl.

The trans-2-ethylidene-cis-3-hexenal: ##SPC4##

has a citrus, albedo-like character which ideally suits it for use incitrus flavors and particularly orange. In orange drink, it imparts ajuice-like character and improves the sweetness.2-Ethylidene-6-methyl-cis-3-heptenal (primarilytrans-2-ethylidene-6-methyl-cis-3-heptenal): ##SPC5##

has a green, floral, slightly cucumber top fragrance note with atwig-like undertone particularly suiting it for use in fragrancecompositions.

Trans-2-ethylidene-trans-3-hexenal, ##SPC6##

has an odor noticeably different from thetrans-2-ethylidene-cis-3-hexenal material disclosed above, having moreof a musty, harsher nuance.

Cis-2-ethylidene-cis-3-hexenal, ##SPC7##

in admixture with trans-2-ethylidene-cis-3-hexenal and the diethylacetal of cis-2-ethylidene-cis-3-hexenal in the followingproportion:Cis-2-ethylidene-cis-3-hexenal70%Trans-2-ethylidene-cis-3-hexenal 20%Diethyl acetal ofcis-2-ethylidene-cis-3-hexenal 10%

at 0.5 ppm imparts a "juicier" note to orange drink flavor. The tastehas dominating fresh green notes with light, spicy backnotes. It has adelicate, green, twiggy, leafy, fruity, aroma note with a naturalcinnamon note on dry-out.

The 2-alkylidene-3-alkenal derivatives and mixtures thereof according tothe present invention can be used to alter, vary, fortify, modify,enhance, or otherwise improve the organoleptic properties, includingflavor and/or aroma, of a wide variety of materials which are ingested,consumed, or otherwise organoleptically sensed. The term "alter" in itsvarious forms will be understood herein to mean the supplying orimparting a flavor character or note to an otherwise bland, relativelytasteless substance, or augmenting an existing flavor characteristicwhere the natural flavor is deficient in some regard, or supplementingthe existing flavor or aroma impression to modify the organolepticcharacter. The materials which are so altered are generally referred toherein as consumable materials.

Such 2-alkylidene-3-alkenal derivatives are accordingly useful inflavoring compositions. Flavoring compositions are herein taken to meanthose which contribute a part of the overall flavor impression bysupplementing or fortifying a natural or artificial flavor in amaterial, as well as those which supply substantially all the flavorand/or aroma character to a consumable article.

The term "foodstuff" as used herein includes both solid and liquidingestible materials for man or animals, which materials usually do, butneed not, have nutritional value. Thus, foodstuffs include meats,gravies, soups, convenience foods malt and other alcholic ornon-alcholic beverages, milk and dairy products, nut butters such aspeanut butter and other spreads, seafoods including fish, crustaceans,mollusks and the like, candies, breakfast foods, baked goods,vegetables, cereals, soft drinks, snack foods, dog and cat foods, otherveterinary products, and the like.

The term "tobacco" will be understood herein to mean natural productssuch as, for example, burley, Turkish tobacco, Maryland tobacco,flue-cured tobacco and the like including tobacco-like or tobacco-basedproducts such as reconstituted or homogenized leaf and the like, as wellas tobacco substitutes intended to replace natural tobacco, such aslettuce and cabbage leaves and the like. The tobaccos and tobaccoproducts include those designed or used for smoking such as incigarette, cigar, and pipe tobacco, as well as products such as snuff,chewing tobacco, and the like.

When the 2-alkylidene alkenal derivatives according to this inventionare used in a flavoring composition, they can be combined withconventional flavoring materials or adjuvants. Such co-ingredients orflavoring adjuvants are well known in the art for such use and have beenextensively described in the literature. Apart from the requirement thatany such adjuvant material be ingestibly acceptable, and thus non-toxicor otherwise non-deleterious, conventional materials can be used andbroadly include other flavor materials, vehicles, stabilizers,thickeners, surface active agents, conditioners, and flavorintensifiers.

The 2-alkylidene alkenal derivatives, or the compositions incorporatingthem, as mentioned above, can be combined with one or more vehicles orcarriers for adding them to the particular product. Vehicles can beedible or otherwise suitable materials such as ethyl alcohol, propyleneglycol, water, and the like. Carriers include materials such as gumarabic, carrageenan, other gums, and the like. The alkenal compoundsaccording to this invention can be incorporated with the carriers byconventional means such as spray-drying, drum-drying, and the like. Suchcarriers can also include materials for coacervating the alkylidenealkenal derivatives (and other flavoring ingredients, as present) toprovide encapsulated products. When the carrier is an emulsion, theflavoring composition can also contain emulsifiers such as mono- anddiglycerides of fatty acids and the like. With these carriers orvehicles, the desired physical form of the composition can be prepared.

When the derivatives are used to treat tobacco products for example, theadditive can be applied in a suitable manner, as by spraying, dipping,or otherwise. They can be applied during the "casing" or final spraytreatment of the tobacco, or they can be applied at some earlier stageof curing or preparation. The quantity of alkylidene alkenal derivativesor mixtures thereof utilized should be sufficient to impart the desiredflavor characteristic to the product, but on the other hand, the use ofan excessive amount of the derivative is not only wasteful anduneconomical, but in some instances too large a quantity may unbalancethe flavor or other organoleptic properties of the product consumed. Thequantity used will vary depending upon the ultimate foodstuff, tobaccoproduct, or other consumable product; the amount and type of flavorinitially present in the product; the further process or treatment stepsto which the product will be subjected; regional and other preferencefactors; the type of storage, if any, to which the product will besubjected; and the preconsumption treatment, such as baking, frying, andso on, given to the product by the ultimate consumer. Accordingly, theterminology "effective amount" and "sufficient amount" is understood inthe context of the present invention to be quantitatively adequate toalter the flavor of the foodstuff, tobacco, or other consumablematerial.

It is accordingly preferred that the ultimate compositions contain fromabout 0.02 parts per million (ppm) to about 150 ppm of 2-alkylidenealkenal derivative or derivatives. More particularly, in foodcompositions it is desirable to use from about 0.05 ppm for enhancingflavors and in certain preferred embodiments of the invention, fromabout 0.2 to 50 ppm of the derivatives are included to add positiveflavors to the finished product. On the other hand, tobacco compositionscan contain as little as 0.5 ppm and as much as 250 ppm depending uponwhether a cigarette tobacco, a pipe tobacco, a cigar tobacco, a chewingtobacco, or snuff is being prepared. All parts, proportions,percentages, and ratios herein are by weight unless otherwise indicated.

The amount of 2-alkylidene alkenal material or materials to be utilizedin flavoring compositions can be varied over a wide range depending uponthe particular quality to be added to the foodstuff, tobacco, or otherconsumable material. Thus, amounts of one or more derivatives accordingto the present invention from about 2 ppm up to 80 or 90 percent can beincorporated in such compositions. It is generally found to be desirableto include from about 10 ppm to about 0.1 percent of the derivatives insuch compositions.

The 2-alkylidene alkenal derivatives of this invention are also usefulindividually or in admixture as fragrances. They can be used tocontribute various fruity, woody, or floral fragrances. As olfactoryagents, the derivatives of this invention can be formulated into or usedas components of a "perfume composition".

A perfume composition is composed of a small but effective amount of an2-alkylidene-3-alkenal derivative according to this invention and anauxiliary perfume ingredient, including, for example, alcohols,aldehydes, ketones, nitriles, esters, and frequently hydrocarbons whichare admixed so that the combined odors of the individual componentsproduce a pleasant or desired fragrance. Such perfume compositionsusually contain (a) the main note or the "bouquet" or foundation-stoneof the composition; (b) modifiers which round-off and accompany the mainnote; (c) fixatives which include odorous substances which lend aparticular note to the perfume throughout all stages of evaporation, andsubstances which retard evaporation, and (d) top-notes which are usuallylow-boiling fresh-smelling materials.

It will thus be apparent that the derivatives according to the presentinvention can be utilized to alter the sensory properties, particularlyorganoleptic properties such as flavor and/or fragrance of a widevariety of consumable materials.

The novel 2-alkylidene alkenals of the present invention can readily beprepared by a number of reaction routes, as will be apparent to thoseskilled in the art from the present disclosure. Thus, they can beprepared by reacting an alkyl metallo acetylide with adialkoxyacetonitrile to form an imine salt, hydrolyzing the imine saltto form 1,1-dialkoxy-3-alkyn-2-one, treating the1,1-dialkoxy-3-alkyne-2-one with an alkylidene triphenyl phosphorane,hydrolyzing the 1,1-dialkoxy-2-alkylidene-3-alkyne so formed in acidicaqueous solution to provide 2-alkylidene-3-alkynal, and reducing thetriple bond to a double bond as by hydrogenation to obtain the novel2-alkylidene-3-alkenal.

It is significant that hydrogenation of the 1,1-dialkoxy-3-alkyne-2-onewill yield, primarily, the isomer 1,1-dialkoxy-cis-3-alkene-2-one whichis then isomerized to the 1,1-dialkoxy-trans-3-alkene-2-one using anappropriate cis-trans isomerization reagent such as a mixture of aceticacid and sodium iodide or potassium iodide (Preferred concentrationrange of alkali metal iodide in acetic acid, from 0.5% up to 2% byweight). It should further be noted that hydrolysis of the1,1-dialkoxy-2-alkylidene-trans-3-alkenal produced as the result ofreaction of the tri-substituted alkylidene phosphorane with the1,1-dialkoxy-3-trans-alkene-2-one will yield a mixture ofcis-2-alkylidene-trans- 3-alkenal andtrans-2-alkylidene-trans-3-alkenal. The cis-2-alkylidene-trans-3-alkenalin the mixture may then be specifically isomerized to thetrans-2-alkylidene-trans-3-alkenal (thus creating a material containingonly the one isomer, to wit: trans-2-alkylidene-trans-3-alkenal) bymeans of an appropriate cis-trans isomerization agent such as a mixtureof acetic acid and an alkali metal iodide such as sodium iodide orpotassium iodide.

Alternatively, the compounds described herein can be produced by aprocess comprising the steps of: (1) reacting an aliphaticα,β-unsaturated aldehyde with an halogen to provide the correspondingα-halo aldehyde derivative; (2) either (i) reacting the said α-haloaldehyde derivative with an alkyl magnesium halide (Grignard reagent)hydrolyzing the resulting product to form a hydroxyhaloalkene anddehydrating the resulting hydroxyhaloalkene to form a trans haloalkadiene or (ii) reacting the said α-halo aldehyde derivative with atrisubstituted alkylidene phosphorane or an alkylidene phosphoroustriamide to provide a mixture of cis and trans halo alkadienes havingstructures: ##SPC8##

(3) either (i) treating either the mixture of said halo alkadieneisomers or said trans halo alkadiene with a metal such as magnesiumthereby forming an organometallic reagent and reacting the saidorganometallic reagent so formed with a trialkyl orthoformate to yieldan acetal which is then hydrolyzed with acid to yield the desiredalkylidene-trans-alkenal or (ii) reacting the mixture of halo alkadieneisomers with an alkyl lithium to form a lithioalkadiene (mixture ofisomers) and then reacting said organometallic reagent with a dialkylformamide or an aryl alkyl formamide followed by acid hydrolysis thusforming a mixture of 2-alkylidene-cis-3-alkenal andalkylidene-trans-3-alkenal or (iii) physically separating the cis haloalkadiene from the trans halo alkadiene and then reacting each isomerindependently with an alkyl lithium to form lithio alkadienes and thenreacting each of said lithio alkadienes with a dialkyl formamide or anaryl alkyl formamide followed by acid hydrolysis forming, separately, analkylidene-trans-alkenal and an alkylidene-cis-alkenal.

In these reactions, the various alkyl and alkylidene substituents arechosen to provide the desired final compounds. The cis-trans isomerratios are controlled by suitable reaction conditions and/or separationtechniques.

The intermediate and/or final products obtained can be purified orisolated by conventional purification after appropriate washing,neutralizing and/or drying as appropriate. Thus, such products can bepurified and/or isolated by distillation, steam distillation, vacuumdistillation, extraction, preparative chromatographic techniques, andthe like.

The following examples are given to illustrate embodiments of theinvention as it is presently preferred to practice it. It will beunderstood that these examples are illustrative, and the invention isnot to be considered as restricted thereto except as indicated in theappended claims.

EXAMPLE I PREPARATION OF 2-ETHYLIDENE-CIS-3-HEXENAL i. Preparation of1,1-Dimethoxy-3-hexyne-2-one

An ether solution of ethylmagnesium bromide is prepared from 7.3 gmagnesium turnings and 32.7 g ethyl bromide. About 20 g ethyl acetyleneis admitted as a gas under a dry ice condenser and the mixture isrefluxed for two hours until gas evolution ceases. The mixture is thencooled below 0°, and 30.3 g of dimethoxy acetonitrile is added in ethersolution.

The mixture is allowed to come to room temperature and stirred for 2hours, during which time the lower layer of the two-phase mixturebecomes almost solid. The mixture is again cooled and treated with 16 mlsulfuric acid diluted with 300 ml water. The layers are separated andthe organic layer is washed successively with saturated aqueous sodiumchloride solution and saturated aqueous sodium bicarbonate solution andthen dried over 4A molecular sieves. Thorough removal of solvent gives35.3 g of yellow oil - 99% pure by GLC (gas-liquid phasechromatography).

ii. Preparation of 2-Ethylidene-3-hexynal Dimethyl Acetal

Ethyltriphenylphosphonium bromide (24.8 g) is stirred with 100 mlbenzene, and 40 ml (1.6 N) butyl lithium in hexane is added over aboutone-half hour with a water bath used to take up the slight heat ofreaction. The mixture (bright orange) is stirred at room temperature for0.75 hour, and 10.0 g of the 1,1-dimethoxy-3-hexyne-2-one is addeddropwise in one-half hour.

After an additional 15 minutes at 40° (water bath) the mixture isfiltered and evaporated at reduced pressure through a fractionationcolumn. The residue is dissolved in isopentane, filtered, and againevaporated to provide 4.3 g of a yellow orange oil. Gas chromatographic,mass spectral and nuclear magnetic resource (NMR) data indicate that themajor peaks are isomers of the desired structures: ##SPC9##

iii. Preparation of 2-Ethylidene-3-hexynal

The acetal isomers so produced are dissolved in 50 ml ether and stirredfor 11/2 hours with 25 ml water containing 2.5 g oxalic acid (roomtemperature). The layers are separated and washed successively withsaturated aqueous sodium carbonate solution and brine, and evaporated atatmospheric pressure through a Vigreux column. After removal of the lasttraces of solvent in vacuo there remains 3.0 g of reddish oil. GC-MS andNMR confirm that the major product is 2-ethylidene-3-hexynal.

iv. Preparation of 2-Ethylidene-cis- 3-hexenal

The 2-ethylidene-3-hexynal so prepared (2.5 g) is dissolved in 20 mlhexane and a small amount of solid is removed by filtration through apad of neutral alumina. The solution is then mixed with 0.25 g Lindlarcatalyst (palladium on calcium carbonate poisoned with lead acetate) andstirred under hydrogen gas at about one atmosphere pressure for 61/2hours. The resulting mixture is filtered and the solvent removed througha Vigreux column. The major component, isolated from aCarbowax(polyethylene glycol)-packed GLC column is demonstrated by IR,NMR, and MS spectral data to be ##SPC10##

The other 2-alkylidene-3-alkenals according to the present invention aresimilarly prepared.

In the following NMR spectra, the shifts in ppm relative to atetramethylsilane standard are measured in carbon tetrachloride at 100MHz. The 2-ethylidene-cis-3-hexenal produced in Example I shows thefollowing:

    Shift    No. of Protons                                                                            Peak      Assignment                                     ______________________________________                                        0.92     3           Triplet   CH.sub.3 --CH.sub.2 --                         1.88                 Doublet   CH.sub.3 --C=C--C=O                            1.92-1.70                                                                              5           Multiplet CH.sub.3 --CH.sub.2 --C=C--                    5.75     2           Multiplet Olefinic protons                               6.61     1           Quartet   CH.sub.3 --CH=C--C=O                           9.41     1           Singlet   Formyl proton                                  ______________________________________                                    

EXAMPLE II

Ten liters of orange juice, concentrated as an aqueous essence by Libby,McNeil & Libby Corp. of Ocala, Florida, is extracted with diethyl etherin a Quickfit Multi-purpose Extractor. After drying the ether extractwith anhydrous megnesium sulfate, the extract is concentrated in aKuderna-Danish apparatus and analyzed by GLC and GLC/MS analysis usingan F&M 5750 Chromatograph equipped with a flame ionization detectoroperating under the following conditions:

    Carrier gas: Helium                                                           Flow rate:   40 ml/min.                                                       Recorder speed:                                                                            0.25 inches/min.                                                 Detector:    F.I.D. at 250°C                                           Column:      10' × 1/8" O.D. 25% Carbowax                                            20 M on 60/80 mesh DMCS-treated                                               Chromosorb WAW                                                   Program rate:                                                                              50°-225° C at 2°/min.                   

The GLC/MS system used has the following components:

    GLC:         Aerograph 1520                                                   Detector:    F.I.D. at 200°C                                           Column:      Support-coated Carbowax 20 M,                                                 0.02" I.D.                                                       Program rate:                                                                              Ambient to 175°C at 2°/min.                        Effluent split:                                                                            6:1 to MS                                                        MS:          Hitachi RMU 6E equipped with                                                  a Watson-Biemann separator in                                                 the MS oven, allowing for                                                     rapid-scan spectra of com-                                                    pounds separated by chroma-                                                   tography.                                                    

Those compounds giving only weak mass spectra are trapped out on asemi-preparative scale under the following conditions:

    GLC:         F & M 700                                                        Detector:    T.C. at 250°C                                             Carrier gas: Helium                                                           Flow rate:   80 ml/min.                                                       Column:      8' × 1/4" O.D. 25% Carbowax                                             20 M on 60/80 mesh Chromosorb                                                 WAW.                                                             Program rate:                                                                              75°-225° C at 2°/min.                   

Compounds trapped from orange juice extract that could not be identifiedby GLC/MS are submitted to NMR and IR for further structural analysis.

A particular compound obtained is an unsaturated aldehyde of molecularweight 124. High resolution MS yields the elemental formula C₈ H₁₀ O andfrom UV (ultraviolet) spectral analysis the compound is shown to be amonosubstituted α,β-unsaturated aldehyde. An NMR-spectrum is recordedand these data, together with the complete mass spectrum, show that thecompound is 2-ethylidene-cis-3-hexenal (substantiallytrans-2-ethylidene-cis-3-hexenal) ##SPC11##

Mass spectral analysis (low resolution) shows the principal m/e ratios:39, 41, 109, 81, 67, 95 . . . 124 (Parent Peak).

The NMR data show (τ in ppm): (solvent-CCl₄):

    τ                                                                              J (cps) No. of protons                                                                            Peak   Assignment                                    ______________________________________                                        9.04 7       3           Triplet                                                                              CH.sub.3 --CH.sub.2 --                        8.12 6       3           Doublet                                                                              CH.sub.3 --CH=C--CHO                          4.34 4       2           Doublet                                                                              cis C.sub.2 H.sub.5 --CH--CH--                                                C                                                                             |                                    3.56 6       1           Quartet                                                                              --CH=C=CHO                                                                    C                                                                             |                                    0.72 --      1           Singlet                                                                              --CH--C--CHO                                  ______________________________________                                    

At 1.5 ppm the 2-ethylidene-3-hexenal obtained has a pleasant freshgreen aroma with a fatty waxy character. At 15 ppm in water the hexenalderivative has a fresh green, waxy character. In a 12% sucrose solutioncontaining 0.1% citric acid at a level of 1.5 ppm it has a fresh green,waxy character reminiscent of citrus fruit rind. At 33 ppm in watersolution it has a clean green, pleasant and intense leafy odor. Thetaste is reminiscent of the white pulpy material, or albedo, of theorange. The odor and taste at 33 ppm of the 2-ethylidene-3-hexenalimpart the aromatic characteristics evident in citrus juices.

EXAMPLE III Preparation of 2-Ethylidene- 6-methyl-cis-3-heptenal

A solution of 5.40 g of isobutylacetylene in 50 ml of diethyl ether istreated with 30 ml of 2.2 N n-butyllithium in hexane at -20°C, and afterseveral minutes the resulting solution is treated with 8.50 g ofdiethoxyacetonitrile and then warmed slowly to room temperature. Afterabout 1.5 hours the dark mixture is cooled and brought to a pH of about2 with ten percent sulfuric acid.

The layers are then separated and the organic layer is washedsuccessively with water and saturated aqueous sodium bicarbonatesolution and then dried over sodium sulfate. Evaporation of the solventprovides 4.6 g of a dark oil, shown by IR and NMR to contain1,1-diethoxy-6-methyl-3-heptyn-2-one.

A solution of ethylidenetriphenylphosphorane is prepared by admixing17.0 g of ethyltriphenylphosphonium bromide with 20 ml of 2.3 Nphenyllithium in a 70:30 benzene: ether vehicle. This is added to theheptynone, with the temperature being held below 30°C with cooling.

A few minutes after the addition is completed, the mixture ispartitioned between water and ether phases. The layers are separated,and the organic phase is dried over sodium sulfate and evaporated. Theresidue is dissolved in hexane and filtered to remove triphenylphosphineoxide. After evaporation of the hexane, the 10.4 g of crude acetalobtained is hydrolyzed to the acetylenic aldehyde in 30 percent aqueousacetic acid.

The crude aldehyde is isolated by partitioning between water and ether;the ether layer is washed successively with water and saturated aqueoussodium carbonate and dried over sodium sulfate; and the solvent isevaporated. The residue is hydrogenated in hexane solution over 1.0 g ofLindlar catalyst (5 percent palladium on calcium carbonate poisoned withlead acetate) at a pressure of about four atmospheres.

The mixture is filtered and the solvent is evaporated to provide 3.8 gof dark oil from which the 2-ethylidene-6-methyl-cis-3-heptenal isisolated by preparative GLC.

The NMR spectrum of the material shows:

    Shift No. of Protons                                                                              Peak       Assignment                                     ______________________________________                                        1.00  6             Doublet    --HC(CH.sub.3).sub.2                           1.70  2             Quartet    =C--CH.sub.2                                   1.88  3             Doublet    --CO--C=C--CH.sub.3                            5.80  2             Multiplet  definic protons                                6.70  1             Quartet    CH.sub.3 --CH=C--C=O                           9.37  1             Singlet    Formyl proton                                  ______________________________________                                    

The material ##SPC12##

has a green, floral, violet slightly cucumber fragrance.

EXAMPLE IV Orange Flavor Formulation

An orange flavor formulation is prepared by admixing:

    Ingredients          Parts                                                    ______________________________________                                        Natural orange oil   13.00                                                    Acetaldehyde         1.50                                                     Ethyl acetate        0.10                                                     Ethyl butyrate       0.50                                                     Propanal             0.10                                                     trans-2-Hexenal      0.10                                                     Ethyl alcohol (95%)  60.00                                                    Fusel oil            0.05                                                     Propylene glycol     24.65                                                    ______________________________________                                    

This is denominated Flavor "A". A second formulation, Flavor "B" isprepared by adding trans-2-ethylidene-cis-3-hexenal (one percent inethanol) to a portion of Flavor "A" in the ratio of 2 parts to 100 partsof Flavor "A".

Each of Flavors "A" and "B" is added in the amount of two ounces pergallon of 32° Baume sugar syrup to produce a syrup for combination withwater to form a drink. The beverage prepared using Flavor "A" is apassable orange beverage of good character, flavor and intensity.

The beverage prepared using Flavor "B" has a much improved flavor. Theimprovement contributed by the ethylidenehexenal is due to:

1. a greater degree of the natural character of freshly squeezed orangejuice

2. an increase in the pulplike notes

3. greater orange juice flavor depth.

EXAMPLE V Preparation of 1,1-Dimethoxy-cis-3-hexene-2-one

Six grams of the 1,1-dimethoxy-3-hexyne-2-one (of Example I) is stirredunder hydrogen gas at one atmosphere in 40 ml hexane containing 0.6 gLindlar catalyst (palladium on calcium carbonate poisoned with leadacetate) and 4.0 g quinoline. The reaction is terminated when onepercent of the starting material (1,1-dimethoxy-3-hexyne-2-one) remains.

The mixture is filtered and the quinoline washed out with dilute aqueoushydrochloric acid. The organic layer is washed with saturated aqueoussodium bicarbonate and then brine; the solvent is evaporated. GLC andNMR of the crude material shows the product is substantially1,1-dimethoxy-cis-3-hexene-2-one having the structure: ##SPC13##

EXAMPLE VI Preparation of 1,1-Dimethoxy-trans-3-hexene-2-one

The crude product produced in Example V is dissolved in 6 ml of aceticacid with 0.1 g of sodium iodide. By GLC on Carbowax(polyethyleneglycol) it is clear that the 1,1-dimethoxy-cis-3-hexene-2-one isconverted to a new material of later retention time. After one-half hourless than 5 percent of "cis" material remains.

The material is isolated by partitioning between water and ether,washing the ether layer successively with aqueous sodium bicarbonate andbrine and then drying over 4A molecular sieves. Evaporation of thesolvent provides 5.0 g of yellow oil. NMR and GLC indicate essentiallyall trans material having the structure: ##SPC14##

EXAMPLE VII

Ethyltriphenylphosphonium bromide (3.71 g) and 6.3 ml of 1.6 N n-butyllithium are mixed in ether solution and 1.58 g of the1,1-dimethoxy-trans-3-hexene-2-one of Example VI is added, while keepingthe internal temperature below 30°C. After a few minutes the mixture isfiltered and the solvent evaporated. A small amount of solid is presentso the residue is dissolved in isopentane, filtered, and againevaporated to give 1.10 g of a yellow-orange oil.

GLC and NMR indicate the presence of two acetals of2-ethylidene-trans-3-hexenal: cis and trans isomers at the ethylidenegroup namely: cis-2-ethylidene-trans-3-hexenal dimethyl acetal andtrans- 2-ethylidene-trans-3-hexenal dimethyl acetal. The acetal materialis dissolved in 2 ml water and 3 ml acetic acid with a small amount ofsodium iodide isomerization reagent. After a few minutes GLC showscomplete hydrolysis. (In the absence of sodium iodide a mixture of cisand trans ethylidene isomers of the aldehydes is obtained).

The product is isolated by partitioning between water and ether. Theorganic layer is washed successively with water, aqueous sodiumbicarbonate, and aqueous sodium chloride and finally evaporated to give0.70 g of an orange oil. The major peak (80%), isolated by preparativeGLC is trans-2-ethylidene-trans-3-hexenal having the structure:##SPC15##

EXAMPLE VIII Preparation of (Z)-2-Ethylidene-(Z)-3-hexenal (orcis-2-ethylidene-cis-3-hexenal)

A slurry of 4.20 g ethyltriphenylphosphoniumiodide in 30 ml ether ismixed with 4.3 ml 2.3N phenyllithium in benzene: ether to provide a deeporange solution. 1,1-Dimethoxy-3-hexyne-2-one as obtained in Example I(1.56 g) is added, keeping the temperature below 30°, and the resultingmixture is stirred one hour. Water and more ether are added, the mixtureis filtered, the layers separated, and the organic layer washed withbrine and then evaporated.

The residue is dissolved in isopentane, filtered, and evaporated to give2.0 g of orange-colored oil. The crude product is hydrogenated at aboutone atmosphere pressure in 10 ml pyridine over 0.2 g palladium on bariumsulfate and the material is re-isolated by partitioning between etherand water. The organic layer is washed several times with water and thensaturated aqueous sodium chloride.

After removal of solvent there is a red-orange oil which contains somepyridine. The major product is isolated by preparative GLC. The trappedmaterial (140 mg.) is hydrolyzed by stirring it in ether solution with 5percent sulfuric acid. After 11/2 hours at room temperature the mixtureis worked up by separating the layers, washing the ether layer withaqueous sodium bicarbonate followed by saturated aqueous sodium chlorideand evaporating through a Vigreux column to give 110 mg of a very palegreen oil with a fresh "green" aroma.

By GLC it is found to contain 10 percent of the acetal, and by NMR, tocontain 20 percent of the stable isomer. The major product is thecis-2-ethylidene-cis-3-hexenal isomer with the structure: ##SPC16##

EXAMPLE IX Tobacco Flavor

Two tobacco flavor formulations are prepared by admixing:

    Formula A                                                                     Ingredients          Parts                                                    ______________________________________                                        Pyroligneous acid    10.00                                                    Solid extract cornsilk                                                                             18.00                                                    Solid extract foenugreek                                                                           3.50                                                     Vanillin             0.15                                                     Cyclotene            0.05                                                     2-Ethyl-3-methylpyrazine                                                                           0.10                                                     Methyl heptynyl carbonate                                                                          0.05                                                     Eugenol              0.10                                                     Trans-2-ethylidene-trans-3-hexenal                                                                 1.00                                                     (Produced by Example VII)                                                     Propylene Glycol     67.05                                                    ______________________________________                                    

    Formula B                                                                     Ingredients          Parts                                                    ______________________________________                                        2-Ethyl-3-methylpyrazine                                                                           0.10                                                     2-Methylvaleric acid 1.00                                                     Methyl heptynyl carbonate                                                                          0.25                                                     Pyroligneous acid    10.00                                                    Trans-2-Ethylidene-cis-3-hexenal                                                                   1.00                                                     (Produced by Example I)                                                       Vanillin             0.02                                                     Solid extract foenugreek                                                                           2.50                                                     Glycerine            16.75                                                    Water                20.00                                                    Solid extract cornsilk                                                                             15.00                                                    Propylene glycol     33.38                                                    ______________________________________                                    

Both Formulas "A" and "B" are useful in tobacco as flavor enhancers.They enhance the sweet, maple, nut-like character and enhance thenatural smell of the tobacco. The tobacco blend on which the flavors areused contains:

    Ingredient               Amount                                               ______________________________________                                        Virginia tobacco         28%                                                  Burley                   48%                                                  Remaining tobaccos (Oriental,                                                  Turkish, stems, reconstituted                                                                         24%                                                   tobacco)                                                                     ______________________________________                                    

EXAMPLE X Perfume Formulation

A perfume formulation is prepared by admixing:

    Ingredients             Parts                                                 ______________________________________                                        Linalool                30                                                    Linalyl acetate         10                                                    Terpineol coeur         5                                                     Nerol coeur             10                                                    Terpinyl acetate        2                                                     Geranyl acetate         2                                                     Neryl acetate           2                                                     Methyl anthranilate     1                                                     Citral                  10                                                    n-Decyl alcohol         1                                                     n-Dodecyl alcohol       5                                                     n-Dodecanal             15                                                    n-Decanal               30                                                    n-Nonanol               3                                                     n-Nonanal               5                                                     n-Decyl acetate         5                                                     n-Dodecyl acetate       3                                                     Trans-2-Ethylidene-cis-3-hexenal                                                                      5                                                     (Produced by Example I)                                                       ______________________________________                                    

The ethylidenehexenal imparts a natural, tart, orange character to thisterpeneless orange perfume formulation.

EXAMPLE XI Strawberry Flavor Formulation

A strawberry flavor concentrate is prepared by admixing:

    Ingredient              Percent                                               ______________________________________                                        Napthyl ethyl ether     0.96                                                  Ethyl methyl phenyl glycidate                                                                         2.88                                                  Vanillin                2.66                                                  2-Methyl-2-pentenoic acid                                                                             3.90                                                  Ethyl acetate           9.58                                                  Isoamyl butyrate        12.25                                                 Ethyl butyrate          26.20                                                 Isoamyl butyrate        40.57                                                 1-(Prop-1'-enyl)-3,4,5- 0.50                                                   trimethoxybenzene                                                            trans-2-ethylidene-cis-3-hexenal                                                                      0.50                                                   (Produced by Example I)                                                      ______________________________________                                    

The concentrate so prepared is dissolved in four times its volume ofpropylene glycol and the mixture is added to a simple syrup at the rateof 8 ounces per gallon of syrup.

The syrup is acidified by the addition of 1.5 ounces of 50% aqueouscitric acid solution to each gallon of syrup. A carbonated beverage isprepared by mixing one ounce of the flavored acidified syrup with fiveounces of carbonated water. The beverage so prepared has an excellentfresh strawberry flavor and is found to be markedly superior to abeverage prepared in the same manner but without thetrans-2-ethylidene-cis-3-hexenal. The beverage prepared without thetrans-2-ethylidene-cis-3-hexenal is found to be lacking in fresh greenflavor notes present in natural strawberry flavor and aroma. Such freshgreen notes are supplied by the trans-2-ethylidene-cis-3-hexenal.

Similar good results can be obtained in altering the organolepticproperties of consumable materials with the other2-alkylidene-3-alkenals of the invention, such as isomers of2-ethylidene-6-methyl-3-heptenal, and the like. The various isomers doexhibit somewhat different organoleptic properties, as will beunderstood from the present disclosure.

What is claimed is:
 1. A composition of matter consisting essentially oftrans-2-ethylidene-cis-3-hexenal having the formula: ##SPC17##